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Auto Shredder Residue (PDF) by zud45877


									                              Materials Characterization Paper
                                      In Support of the
                                  Proposed Rulemaking:
         Identification of Nonhazardous Secondary Materials That Are Solid Waste
                                  Auto Shredder Residue
                                           March 18, 2010

1.     Definition of Auto Shredder Residue

Auto shredder residue (ASR) is the 15 to 20 percent of vehicle materials remaining after a
vehicle has been shredded and removed of reusable parts and metals. ASR is composed of
plastics, rubber, foam, residual metal pieces, paper, fabric, glass, sand, and dirt (EPA, 2008;
USCAR, 2008). It is also termed “auto fluff” or “auto shredder fluff.”

2.     Annual Quantities of Auto Shredder Residue Generated and Used

       (1) Sectors that generate auto shredder residue
              Auto shredding operations, categorized under NAICS 423930 (Recyclable
              Material Merchant Wholesalers) are the only known generators of ASR. There
              are approximately 185 to 200 auto shredders in the U.S. (Boughton, 2006;
              DeGaspari, 1999).

       (2) Quantities of auto shredder residue generated
             The U.S. generates approximately 5 million tons of ASR annually and nearly all
             of this is landfilled (Hook, 2008; EPA, 2008).

       (3) Trends in generation of auto shredder residue
              Quantities of ASR produced are likely to increase in the future, due to the
              growing number of cars scrapped each year and the increased use of plastics in
              automobile production (Nourreddine, 2007).

3.     Uses of Auto Shredder Residue

       (1) Combustion uses of auto shredder residue
             Currently, nearly all ASR is landfilled and a small portion is incinerated,
             primarily owing to the lack of cost-effective technology to process and use ASR
             (Argonne, 2003). An additional barrier to using it as fuel is that unprocessed ASR
             has high ash, heavy metal, and chlorine content (Boughton, 2006).

               Approximately 20 to 50 percent of dry ASR is combustible, including plastics,
               fabric, and rubber; incombustibles include metals, glass, dirt, and ash. The first
               step in processing ASR for fuel use would be removal of incombustibles (Tai,
               2006; Boughton, 2006).
                                                                            Auto Shredder Residue

            ASR could potentially be used as a supplement to conventional fuel in cement
            kilns or steel mill blast furnaces. Use of ASR in cement kilns may be more easily
            accomplished than in boilers and other combustion units because kilns can
            tolerate high ash content and heterogeneous materials. A recent evaluation of
            ASR use in cement kilns conducted by the California Department of Toxic
            Substances Control suggests that, despite the obstacles of separating combustibles
            from incombustibles and reducing contaminant concentrations, processing ASR
            for use in cement kilns would be cost-effective, due largely to the avoided
            transportation costs and tipping fees associated with landfilling (Boughton, 2006).
            This effect, however, would vary throughout the U.S. due to regional differences
            in transportation distances and landfill tipping fees. In addition, the Environment
            and Plastics Industry Council and the American Plastics Council have conducted
            research investigating methods to process ASR into a more suitable fuel for steel
            mill blast furnaces (Cirko, 1999).

     (2) Non-combustion uses of auto shredder residue
           As mentioned above, nearly all ASR is landfilled, and it appears that virtually no
           ASR is currently beneficially used. 40 CFR 761.62, “Disposal of PCB bulk
           product waste,” states, however, that ASR may be disposed in landfills as daily
           cover or used under asphalt as part of road bed, but no data on such applications
           have been identified. In addition, other potentially recoverable materials
           contained in ASR and their potential uses include:

                •   Foam, which accounts for 5 percent of vehicles by weight but 30 percent
                    by volume, can be rebounded and used as carpet padding and seat cushions
                    in cars (DeGaspari, 1999).

                •   Plastics, which account for 30 percent of vehicle weight, can be recycled
                    into battery trays (Hook, 2008).

                •   Iron oxide residuals can be used as an ingredient in cement production
                    (Argonne, 2003).

     (3) Quantity of auto shredder residue landfilled
           Sources generally state that most, if not all, ASR is landfilled (Hook, 2008; EPA,
           2008; Boughton, 2006). This would suggest that approximately 5 million tons of
           ASR are landfilled annually.

4.   Management and Combustion Processes

     (1) Types of units using auto shredder residue
            Currently most ASR is landfilled, though development of methods to use ASR is
            underway. Potential users of ASR include:
                • Cement kilns
                • Steel mill blast furnaces
                • Car manufacturers

                                                                       Auto Shredder Residue

(2) Sourcing of auto shredder residue
       Approximately 12 to 15 million automobiles are disposed of annually in the U.S.
       (USCAR, 2008). Once automobiles reach the end of their useful life, they are
       sent to one of roughly 12,000 auto dismantlers, where the car is stripped of
       reusable parts. The stripped cars are then sent to one of approximately 185 to 200
       auto shredding operations, where hammermills crush them into smaller pieces.
       Metal chunks are recovered and sold to metal scrap processing industries
       (DeGaspari, 1999). Over 25 million tons of materials are recovered for reuse or
       recycling. The remaining material comprises the ASR (EPA, 2008).

(3) Processing of ASR for combustion uses
       Unprocessed ASR has poor fuel characteristics, due to its high ash content; the
       presence of contaminants, including heavy metals, chlorine, and PCBs; and the
       heterogeneity of ASR, which is made up of approximately 20 to 50 percent
       incombustibles (Tai et al, 2006; Boughton, 2006). Prior to use as a fuel, ASR
       would therefore require significant separation and processing to isolate
       combustible materials with low ash content and low contaminant concentrations.

       The California Department of Toxic Substances Control has developed methods
       for separating and beneficiating the ASR stream to make it suitable fuel for
       cement kilns. First, trommels are used to create ASR sub-streams of different
       sizes, which also results in some rough separation by material (e.g., residual metal
       fines are small, while plastic and rubber pieces are larger). Then further
       separation is performed by hand and through density separation techniques, with
       the goal of developing a mixture of ASR that maximizes energy content, while
       minimizing content of ash, chlorine, and heavy metals. This process achieves a
       mixture of ASR that represents 30 percent of the original mixture and has a
       heating value of approximately 13,240 Btu per pound, which is higher than that of
       most types of coal (Boughton, 2006).

       The Environment and Plastics Industry Council and the American Plastics
       Council coordinated with eight automobile shredders to develop a procedure for
       processing ASR for use in steel mill blast furnaces. This process, which would
       reduce the ash content of ASR and increase its energy content, would yield an
       ASR material with a thermal value of approximately 10,000 Btu per pound
       (Cirko, 1999).

       Researchers in Taiwan have taken further steps in the development of ASR for
       fuel use by processing it into ASR-derived fuel (ASRDF) rods, for ease of
       transportation and storage. The first step in this process is the manual removal of
       glass, electrical wires, dirt and gravel, and metal components, yielding an ASR
       mixture with a heat value of approximately 10,500 Btu/pound. Then the ASR is
       placed into an extrusion apparatus, where it is exposed to high pressure and
       temperature and formed into rods. The extrusion process reduces the heat value

                                                                            Auto Shredder Residue

            by approximately 1,800 Btu/pound, but the rods have a higher heat per unit of
            mass than does the un-compacted material (Tai et al, 2006).

     (4) Processing of ASR for non-combustion uses
            As indicated above, virtually no ASR is used for non-combustion applications
            because of the heterogeneity of ASR material. The Department of Energy’s
            Argonne National Laboratory, however, has recently developed methods for
            separation, recovery, and use of ASR. After undergoing separation and cleaning
            processes, certain constituent materials of ASR can be recovered. Argonne has
            found that up to 60 percent of ASR can be recovered as usable material (Hook,

            The process developed by Argonne begins with bulk separation through use of a
            two-part trommel, which separates ASR into three streams: a polymers-
            concentrated stream (45 percent of ASR, by weight), foam (10 percent), and small
            inorganic particles (45 percent). The first part of the trommel is equipped with a
            fine mesh, through which the inorganic particles are separated. The second part
            of the trommel has larger slots, through which plastics and rubber pieces fall,
            leaving behind the foam. Each of these three streams is then further processed to
            extract the useful materials. The polymers undergo density separation and froth-
            flotation to be separated by type, in order to recover those plastics and rubbers
            that are present in the largest volumes or that have the highest value. The foam,
            which contains automotive fluids and some residual inorganic particles, is run
            through a series of stages for cleaning, and is then dried and baled. The inorganic
            particles, which include metal residuals, dirt, and glass, are exposed to magnets to
            extract iron oxides, and the rest is discarded (Argonne, 2003; DeGaspari, 1999)

            At present, Argonne’s system is not yet used in the United States, though it has
            been licensed to Salyp N.V., a recycler in Belgium, which completed construction
            of an ASR recycling plant in 2003 (DeGaspari, 1999; Hook, 2008).

     (5) State regulatory status of auto shredder residue beneficial use
            According to state responses to a 2006 survey by the Association of State and
            Territorial Solid Waste Management Officials (ASTSWMO), Florida has
            approved ASR as landfill initial cover, while Kentucky, Maryland, Massachusetts,
            Michigan, New Hampshire, New York, Tennessee, Virginia, and Wisconsin have
            approved it as an alternate daily landfill cover. ASTSWMO also reports that
            Michigan and Texas have approved ASR for liquid solidification. Wisconsin has
            pre-approved ASR for landfilling and Washington has pre-approved ASR in a few
            cases as alternative daily cover (ASTSWMO, 2007).

5.   Commodity Composition and Impacts

     (1) Composition and energy content of auto shredder residue
           (a) Composition:
                  30 percent polymers (by weight)

                                                                                              Auto Shredder Residue

                           10 percent residual metals
                           5 percent foam
                           The remainder is a mixture of glass, wood, paper, sand, dirt, rocks, and
                           automotive fluids (Hook, 2008; DeGaspari, 1999)

                  (b) Energy content:
                         Unprocessed ASR – roughly 5,000 Btu/pound (Boughton, 2006)
                         After removal of incombustibles – 9,000-10,500 Btu/pound (Tai et al,
                         2006; Cirko, 1999)
                         After removal of incombustibles and additional processing to isolate
                         combustibles with high energy content - 13,240 Btu/pound (Boughton,

         (2) Impacts of auto shredder residue use
             a. Cost impacts
                The recycling and use of ASR may result in cost savings. The California
                Department of Toxic Substances Control conducted an economic analysis of ASR
                use in cement kilns, and found that the processing and use of all annually-
                generated ASR for cement kilns would save the cement manufacturing industry
                $50 million per year through reduced energy costs. It would also save auto
                shredding operations $20 million per year in avoided landfilling costs. While the
                costs of processing the ASR for use in cement kilns would also amount to $20
                million per year, auto shredding operations could also generate $20 million per
                year in revenue from the sale of copper, which is extracted during processing
                (Boughton, 2006). Alternatively, if all ASR were to be used as a fuel in steel mill
                blast furnaces, it could reduce fuel costs for operators by as much as $20 per ton
                of coke replaced (Cirko, 1999). 1

                  Regarding the use of ASR for non-fuel applications, savings could be achieved
                  through avoided production of virgin foam. While clean recycled foam sells for
                  $0.25 to $0.30 per pound, virgin foam costs approximately $1 per pound
                  (Argonne, “Recovering Foam from Scrapped Autos”). In addition, the savings
                  referenced above with respect to copper recovered from ASR prior to its use as a
                  fuel would presumably apply to beneficial use for non-fuel applications as well.
                  Savings could also be realized through the re-use of other materials contained in
                  ASR, but no information on these savings has been identified.

             b. Environmental impacts
                Comprehensive data on the environmental impacts of using ASR as a substitute
                for virgin materials have not been identified. Available data sources, however,
                contain the following information regarding these impacts:

           The figures presented in this paragraph could change over time, owing to variations in virgin fuel prices,
landfilling costs, and the value of copper. The California Department of Toxic Substances Control assumed the
following prices and values: a price of $50/ton of coal, landfilling tipping fee of $17/ton, trucking cost of $2/mile,
average distance to landfill of 20 miles, and $0.85/pound value of scrap copper wiring.

                                                                                               Auto Shredder Residue

                      •   Argonne estimates that the recovery and reuse of polymers and residual
                          metals, for non-fuel applications, from all of the ASR produced annually in
                          the United States would save the equivalent of 24 million barrels of oil per
                          year and reduce CO2 emissions by 12 million tons (Hook, 2008). 2

                      •   Benefits from the use of ASR as a fuel may also include reduced CO2
                          emissions from substitution for coal (Boughton, 2006). The California
                          Department of Toxic Substances Control estimates that if all ASR produced
                          in the United States were processed for use in cement kilns, it could
                          potentially provide 6 percent of the cement industry’s energy needs and
                          result in the conservation of approximately one million tons of coal

                      •   Additionally, diverting ASR from landfills prevents potential leachate
                          contaminated with ASR constituents (Boughton, 2006).

                  It is important to note that the presence of contaminants in ASR raises concerns
                  about emissions from the combustion of this material. The California Department
                  of Toxic Substances Control found that, while its processing techniques for
                  developing ASR as a fuel for cement kilns minimizes contaminant concentrations,
                  chlorine and heavy metals still remain at levels that may limit the rate at which
                  ASR may be fed into a cement kiln (Boughton, 2006). Additionally, although
                  ASRDF rods have low heavy metals concentrations, the chlorine content of these
                  rods may represent a potential hazard (Tai et al, 2006). 3 Additional efforts to
                  eliminate PVC from ASR prior to its combustion for fuel purposes may mitigate
                  chlorine-related contamination issues, given that PVC is typically 50 percent
                  chlorine (Boughton, 2006).

           It is unclear whether these figures represent estimates of direct or lifecycle energy and emissions impacts.
In addition, it is unclear whether this CO2 emissions value is net of the emissions associated with burning ASR.
           In the Taiwanese study, no efforts were taken to remove combustibles with high chlorine contents, so
chlorine contamination is more of a concern than in the California study. Yet, in the Taiwanese study, metals were
removed more thoroughly by hand, so the rods present less of a threat of metal concentrations.

                                                                              Auto Shredder Residue


Argonne. 2003. “Materials Recovery from Auto Shredder Residue.”

Argonne. “Recovering Foam from Scrapped Autos.” Argonne National Laboratory

Association of State and Territorial Solid Waste Management Officials (ASTSWMO). 2007,
       2006 Beneficial Use Study Report, published by Association of State and Territorial Solid
       Waste Management Officials.

Boughton, Robert. 2006. “Evaluation of shredder residue as cement manufacturing feedstock.”
      California Department of Toxic Substances Control.

Cirko, Cathy. 1999. “Auto shredder residue potential fuel for steel mill blast furnaces.”
       Canadian Chemical News, September 1, 1999.

DeGaspari, John. 1999. “From trash to cash: A new process reclaims former unrecoverables in
      the residue of scrapped vehicles.” Mechanical Engineering Magazine Online

Hook, Brian R. 2008. “Auto shredder residue recycling researched.”

Nourreddine, Menad. 2007. “Recycling of auto shredder residue.” Journal of Hazardous
      Materials 139(3): 481-490.

Tai, Hua-Shan, Sheng-Cheng Chang, and Wan-Shan Su. 2006. “Investigation of the Derived
       Fuel Rod Formation from Auto Shredder Residue Using an Extrusion Apparatus.”
       Environmental Progress 25(3): 235-252.

United States Council for Automotive Research LLC (USCAR). 2008. “Did you know that cars
       are the most recycled product in America?” Press Release of USCAR

United States Environmental Protection Agency (EPA). 2008. “Automotive Parts,” at Common
       Wastes & Materials <>.


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